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• Data centres in the EU – Facts & Figures

A comprehensive assessment of the energy efficiency and sustainability of data centres in the EU based on measured values was carried out for the first time. This was based on data submitted by data centres to the EU as part of a reporting obligation.

A consortium consisting of the Borderstep Institute, EY and the Austrian Institute of Technology (AIT) analysed the information submitted and assessed the current status of data centres in the EU based on sustainability and performance indicators.

The report “European Commission: Directorate-General for Energy, AIT, Borderstep and EY, Assessment of the Energy Performance and Sustainability of Data Centres in the EU – First Technical Report, Publications Office of the European Union, 2025” is available to download free of charge.

European Green Deal & Energy Efficiency Directive

With the European Green Deal, the EU is pursuing the goal of becoming climate-neutral by 2050.

To achieve this, it aims to:

• drastically reduce greenhouse gas emissions,

• promote sustainable business practices, and

• actively protect the environment, resources, and biodiversity.

Energy efficiency contributes to reducing overall energy consumption. It is therefore of central importance for the realisation of the EU’s climate protection goals.

The Energy Efficiency Directive defines the targets and measures for data centres. These measures ensure that digitalisation and sustainability go hand in hand:

• Climate neutrality by 2030: Operators should run data centres in the EU in a climate-neutral manner by 2030 at the latest.
• Increase energy efficiency: The aim is to significantly reduce the energy consumption of data centres, e.g. through more efficient cooling, better hardware and optimised management.
• Utilise renewable energies: Renewable energy sources cover the electricity requirements of data centres wherever possible.
• Promote waste heat utilisation: Operators use the waste heat generated during operation sensibly, for example to heat buildings.
• Transparency and monitoring: Operators should regularly report on the energy consumption and environmental impact of their data centres.

Key figures on the sustainability of data centres

For the first time, researchers have now systematically collected data from EU data centres. They use recognized industry key performance indicators (KPIs) to draw well-founded conclusions about the sustainability of data centres based on these surveys. These enable a comparable and objective assessment of key aspects such as energy efficiency, resource utilisation and environmental impact.

PUE (Power Usage Effectiveness): How efficiently does a data centre use energy?

The PUE key figure indicates the additional energy required by the data centre infrastructure. It is therefore the key indicator for evaluating the energy efficiency of data centre infrastructure and the building.

The PUE figure indicates the additional energy required by the data centre infrastructure. It is therefore the key indicator for evaluating the energy efficiency of data centre infrastructure and the building.

A PUE of 1.5 means that for every kilowatt hour (kWh) used for servers, storage and network devices, an additional half kWh is consumed for data centre infrastructure such as cooling, power distribution and lighting. It therefore shows the relationship between the total energy consumption of a data centre and the energy consumption of the IT hardware.

Experts consider a low PUE value efficient, but they use it only to indicate the additional energy consumption of the building and cooling infrastructure—not of the entire data centre.

What is the relationship between total energy consumption and energy consumption of information technology?

The current reporting shows PUE average values of between 1.15 and 1.66 for the member states, while the EU as a whole has a value of 1.36. To enlarge the values, please open the image in a new tab.

WUE (Water Usage Effectiveness): How efficiently is water used in the data centre?

The WUE key figure measures how efficiently a data centre uses water, expressed in cubic metres per megawatt hour of energy consumption for information technology (m3/MWh). A lower WUE value indicates higher water efficiency, which means that less water is used for the same computing power.WUE measures how efficiently a data centre uses water, expressed in cubic metres per megawatt hour of information technology energy consumption (m3/MWh). A lower WUE value indicates higher water efficiency, which means that less water is used for comparable IT capacity.

The water consumption of data centres depends primarily on the cooling technology used: Facilities that use evaporative systems consume a lot of water, while facilities that rely on dry coolers operate with little or no water.

Different conditions in Europe are not taken into account

The WUE is a helpful indicator for uniformly assessing the water consumption of data centres. However, the collected WUE Categories 1 and 2 are not showing what type of water is used or how scarce water is in the respective region. Possible effects on the local environment are also not taken into account – and there are very different conditions in Europe.

The current reporting shows WUE values of between 0.07 m³/MWh and 1.28 m³/MWh for the member states. The EU as a whole has a value of 0.58 m³/MWh. To enlarge the values please open the image in a new tab.

ERF (Energy Reuse Factor): How energy efficient is a data centre?

REF: The Energy Reuse Factor assesses how energy-efficient a data centre is. It indicates how much of the energy consumed – in particular through the waste heat generated – is reused for other purposes. For example, this surplus energy can heat buildings, warm water, or feed district and local heating networks.

The ERF assesses how extensively the theoretical waste heat generated by a data centre is used. It indicates how much of the energy consumed – in particular through the waste heat generated – is reused for other purposes. This surplus energy can, for example, be used to heat buildings, to heat water or to feed into district and local heating networks.

The value is between 0 and 1: An ERF of 1 means that all the energy used is completely reused. However, this is hardly achievable in practice, as energy is always lost during the transport or utilisation of waste heat and also depends on the demand of the heat consumer. An ERF of 0, on the other hand, means that no energy is recovered.

The use of waste heat from data centres offers a great opportunity

According to the Borderstep Institute, the electricity consumption of data centres in Germany alone was 20 terawatt hours in 2024. The digital association Bitkom estimates that the 90 large German data centres currently generate largely unused waste heat, which could theoretically supply 350,000 homes in Germany.

In the current reporting, the ERF values for the member states are between 0 (countries without waste heat utilisation from data centres in the reported data) and 0.457. The EU as a whole has a value of 0.205. However, the values here relate exclusively to data centres that use waste heat at all. In relation to all data centres, the value is 0.018. This means that data centres currently reuse only around 1.8 percent of their waste heat.To enlarge the values please open the image in a new tab.

REF (Renewable Energy Factor): How much renewable energy is used?

REF: The Renewable Energy Factor evaluates the proportion of a data centre’s energy consumption from renewable sources. It is expressed as a ratio or percentage, where a REF of 1.0 means that all energy consumption comes from renewable sources.

Data centres in the EU are increasingly relying on renewable energies

In many EU member states, there is an encouraging trend: data centres are increasingly using renewable energy, achieving an average REF of 0.87 across the EU.

This means that 87 percent of the electricity used by data centres comes from renewable sources. By comparison, the share of renewable energy in total electricity consumption in the EU is currently around 45 per cent. This means that data centres are already making a significantly above-average contribution to the energy transition in many countries.

The current reporting shows REF values of between 0.36 and 1.00 for the member states. The EU as a whole has a value of 0.86. This means that 86 percent of the energy used by data centres comes from renewable energy sources according to the definition of the REF (i.e. including certificates of origin). To enlarge the values please open the image in a new tab.

Why should we take a holistic view of the energy efficiency of data centres? PUE & Co. in interaction

Why PUE alone is not enough? Increases in PUE efficiency can have unintended consequences for other sustainability indicators. A holistic assessment must therefore include several indicators:

PUE: The PUE indicator shows how efficiently a data centre uses energy. It is the key indicator for evaluating the energy efficiency of data centres.
>ERF: The ERF – the proportion of energy recovered and utilised elsewhere – is also not directly related to the PUE. Energy-efficient cooling methods can, for example, make it more difficult to utilise waste heat and thus reduce the ERF.

REF: A low PUE says nothing about the origin of the energy used. A sustainable overall picture only emerges if the proportion of renewable energy is also high.
>WUE: If data centres improve the PUE, e.g. by switching to water-based cooling, this can increase water consumption – and thus worsen the WUE value.

The data collected for the first time provides a clearer picture of where European data centres stand in terms of sustainability - and how their future can be effectively shaped.

How can data centres become greener?

Many data centres state that they use “green electricity” – i.e. electricity from renewable sources such as wind or solar. Until now, companies have often ensured this using so-called guarantees of origin. Critics are increasingly questioning this method, as it does not always ensure that new green electricity is actually generated from renewable sources.

What are better ways to support the transition to a climate-neutral energy system?

Better ways to support the transition to a climate-neutral energy system:

Green electricity contracts (PPAs). Allow companies to purchase electricity directly from new wind or solar power plants and thereby actively support the expansion of renewable energies.

Hourly coordination of electricity generation and consumption. If data centres coordinate their consumption precisely with the times when green electricity is actually available, this helps the entire electricity system to become more climate-friendly.

On-site power generation. When data centres generate their own electricity from solar energy or other sources, they produce it exactly where it is needed. This relieves the power grid, reduces transmission losses, and saves space because operators do not have to build large plants far away.

Classification of the electricity consumption of data centres in the EU

In the first round of surveys (2023), researchers recorded data centres consuming a total of 14,088 GWh (14.09 TWh) of energy (see report p. 80).

Compared to the datacentermap.com database, a completeness of the first reporting of ~36% is assumed (see report p. 24). Datacentermap.com relies largely on voluntary entries and does not represent a comprehensive database of all data centres.

Furthermore, operators of data centres and IT rooms under 500 kW do not have to report their data. This means that the current figures do not contradict the 45-65 TWh from the meta-study by Kamiya, G. & Bertoldi, P. (2024) or the bottom-up estimate based on server sales of ~87 TWh forecast for 2025 in Hintemann (2020).

Publications on the topic